[SV650rules]

Most cooker hoods are designed to be either vented externally or will blow back into same room ( can move a baffle inside hood ), they have a normal grease filter and a carbon one ( carbon one needed for internal venting), not ideal to blow back into room but some people do it because they either can't or don't want to knock a hole in the wall, or don't want to blow hot air outside.

A light that blows a circuit breaker when it is turned off ( is it earth leakage type or just overcurrent ? ) is a worry, don't know what electrician meant about ring main not being right, they are pretty simple and should be checked for earth and neutral crossed.

As for damp, buy a dehumidifier, it is a good thing to have in any house as a dry house has a lot less problems than a damp one, the humidity sensing type ( ebac are made in UK ) switch off when humidity reaches a certain level, cost about a pound a week to run, and they give more heat back to the house than they use in power ( when water is condensed it give up the energy it took to evaporate it, which is how reverse cycle air conditioning returns over 2KW in heat for every 1KW of energy used to power it) and dry walls and ceilings are better insulators than damp ones.